Composite substrate and circuit board

Abstract

The present invention provides a composite substrate and a circuit board. The composite substrate includes a first resistance layer and a base layer. The first resistance layer is laminated on at least one surface of the base layer. The surface of the base layer facing the first resistance layer has a plurality of protrusions. The surface roughness Ra of the base layer having the protrusions is 0.5 μm to 5 μm, and the number of protrusions is 0.1×10 3 pieces / mm to 3×10 3 pieces / mm. Due to the above limitations, the uniformity of the first resistance layer deposited on the surface of the base layer is improved, thereby improving the sheet resistance uniformity of the first resistance layer, which is useful for the manufacture of high-precision embedded resistors and beneficial to the performance of circuit boards and even electronic components.

Description

Technical Field

[0001] The present invention relates to the technical field of composite substrates, and particularly to composite substrates and circuit boards.

Background Art

[0002] With the rapid development of wireless communication and electronic devices, electronic devices are moving towards precision, miniaturization, and thinning. Therefore, it is required to make the components inside the electronic devices as small and thin as possible. The resistance elements inside the electronic devices have evolved from pin-type plug-in resistors to chip resistors, and then from chip resistors to embedded resistors, and are gradually becoming thinner. The application process of the embedded resistor is generally to attach a composite substrate to a circuit board and form the embedded resistor by an etching process. The composite substrate includes a base layer and a resistance layer located on one surface of the base layer. The surface of the resistance layer away from the base layer is suitable for attaching to the circuit board.

[0003] However, the sheet resistance uniformity of existing composite substrates is low, which is disadvantageous for the manufacture of high-precision embedded resistors.

Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is how to improve the sheet resistance uniformity of the embedded resistor and provide a composite substrate and a circuit board.

[0005] The present invention provides a composite substrate, which includes a first resistance layer and a base layer. The first resistance layer is laminated on at least one surface of the base layer. The surface of the base layer facing the first resistance layer has a plurality of protrusions. The surface roughness Ra of the base layer surface with protrusions is 0.5 μm to 5 μm, and the number of protrusions is 0.1×10 3 pieces / mm to 3×10 3 pieces / mm.

[0006] Preferably, the axis at the center of the top of the protrusion in the base layer is the central axis of the protrusion, and the horizontal distance between the central axes of adjacent protrusions is 1 μm to 20 μm.

[0007] Preferably, the protrusions on the surface of the base layer are distributed such that the ratio of the number of protrusions with a distance D between the central axes of adjacent protrusions is 70% or more, where 2 μm ≤ D ≤ 11 μm.

[0008] Preferably, the protrusions on the surface of the base layer are distributed such that the ratio of the number of protrusions with 2 μm ≤ D < 4 μm is 10% to 40%, the ratio of the number of protrusions with 4 μm ≤ D < 6 μm is 40% to 70%, the ratio of the number of protrusions with 6 μm ≤ D < 8 μm is 10% to 40%, the ratio of the number of protrusions with 8 μm ≤ D < 11 μm is 5% to 20%, and the ratio of the number of protrusions with 2 μm ≤ D < 11 μm is 100% or less.

[0009] Preferably, the thickness of the first resistive layer is 5 nm to 3 μm.

[0010] Preferably, the material of the base layer is a conductive material or a dielectric material, and the conductive material includes at least one of copper, aluminum, titanium, zinc, iron, nickel, chromium, cobalt, silver, and gold.

[0011] Preferably, the first resistive layer contains at least one element of Ni, Cr, Si, P, N, Ti, Pt, Ta, Mo, Sn, and O.

[0012] Preferably, the material of the first resistive layer includes at least one of NiCrSi, NiCrAlSi, NiP, AlN, NiCr, TiN, Pt, Cr, Cr - SiO, Cr - Si, Ti - Si, Ti - W, TaN, Mo, and Ni - Sn.

[0013] Preferably, the composite substrate includes a film layer located on the surface of the first resistive layer away from the base layer.

[0014] Preferably, the thickness of the film layer is 0.5 μm to 100 μm.

[0015] Preferably, a conductive layer is provided on a side of the film layer away from the first resistive layer.

[0016] Preferably, the conductive layer is a single-layer conductive layer or a multi-layer conductive layer.

[0017] Preferably, a second resistive layer is provided between the film layer and the conductive layer.

[0018] Preferably, the first resistive layer is formed by one or more methods among electroplating, chemical plating, physical vapor deposition, and chemical vapor deposition.

[0019] The present invention also provides a circuit board including the above composite base material.

[0020] The technical solution of the present invention has the following advantages.

[0021] In the composite base material and the circuit board according to the present invention, by controlling the surface roughness and the number of protrusions of the base layer, the uniformity of the first resistive layer deposited on the surface of the base layer is improved, and further the sheet resistance uniformity is improved. Furthermore, when the resistor manufactured in this way is applied to the circuit board, a good bonding effect is obtained, and the structural stability of the electronic device is improved.

Brief Description of the Drawings

[0022] To more clearly explain the specific embodiments of the present invention or the technical solutions of the prior art, the drawings necessary for explaining the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative efforts.

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Mode for Carrying Out the Invention

[0023] Hereinafter, the technical solution of the present invention will be clearly and completely described with reference to the drawings. Obviously, the described embodiments are some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present invention.

[0024] In the description of the present invention, the directions or positional relationships indicated by terms such as "upper", "lower", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, and are merely for the convenience of explaining the present invention and simplifying the description, and it is not intended to imply or suggest that the mentioned devices or elements must have a specific direction and be constructed and operated in a specific direction. Therefore, it should not be construed as limiting the present invention.

[0025] In order to improve the peel strength between the composite base material and the circuit board and make it difficult to peel them off, it should be understood that usually, the base layer is processed to form a plurality of protrusions on one surface of the base layer. As a result, one surface of the base layer has a certain roughness, and the resistive layer deposited on the rough surface of the base layer has a corresponding rough surface.

[0026] The applicant has discovered that if the protrusions on the surface of the base layer are too numerous or too few, or if the roughness of the base layer is too large or too small, the deposition uniformity of the resistive layer will decrease. As a result, the sheet resistance uniformity of the resistive layer will also decrease. The sheet resistance uniformity of existing composite films is approximately ±10%, which is not useful for manufacturing high-precision embedded resistors and will affect the performance of circuit boards and even electronic components. Specifically, if the number of protrusions is too large, there will be more resistive materials that cannot be deposited in the area between adjacent protrusions. As a result, the deposition uniformity of the resistive layer will decrease. On the other hand, if the number of protrusions is too small, the peel strength between the composite substrate and the circuit board will be low, and the composite substrate cannot be stably fixed on the circuit board.

[0027] Based on this, referring to FIGS. 1 and 3, this embodiment provides a composite substrate including the following.

[0028] A base layer 1, at least one surface of the base layer 1 has a plurality of densely arranged protrusions 11, the surface roughness Ra of the base layer 1 having the protrusions 11 is 0.5 μm to 5 μm, and the number of the protrusions 11 is 0.1×10 3 pieces / mm to 3×10 3 pieces / mm. The surface roughness Ra of the base layer 1 having the protrusions 11 is preferably 0.5 μm to 1.5 μm.

[0029] A first resistive layer 2, the first resistive layer 2 is located on the surface of the base layer 1 having the protrusions 11, the thickness of the first resistive layer is very thin, the shape of the first resistive layer is a shape covering the base layer, and the shapes of both are basically the same. The roughness of the base layer in the present invention is measured from the side of the first resistive layer away from the base layer. FIG. 2 is a SEM scanning diagram of the base layer, and the magnification of FIG. 2 is 5000 times. In FIG. 3, although the first resistive layer is deposited on the surface of the base layer having protrusions, since the first resistive layer is thin, it cannot be seen in FIG. 3.

[0030] By restricting the number of the protrusions 11, as much resistive material as possible can be deposited in the regions between the adjacent protrusions 11. By restricting the surface roughness of the base layer 1, the uniformity of the first resistive layer 2 deposited on the surface of the base layer 1 is improved, thereby improving the sheet resistance uniformity of the first resistive layer 2. The sheet resistance uniformity is in the range of about ±5%, which is useful for manufacturing high-precision embedded resistors and beneficial to the performance of circuit boards and further electronic components.

[0031] Furthermore, the first resistive layer 2 is arranged in the same shape as the base layer 1, that is, the surface of the first resistive layer 2 also has corresponding protrusions 11. Also, by restricting the number of the protrusions 11, an appropriate peel strength between the composite base material and the circuit board is ensured. Therefore, the composite base material can be stably fixed on the circuit board, the composite base material is less likely to peel off from the circuit board, and the structural stability of the electronic device is improved.

[0032] Preferably, the number of the protrusions 11 is 0.1×10 3 pieces / mm to 2×10 3 pieces / mm. As an example, the number of the protrusions 11 can be 0.1×10 3 pieces / mm, 0.5×10 3 pieces / mm, 1×10 3 pieces / mm, 1.5×10 3 pieces / mm, 2×10 3 pieces / mm, or within the range of any combination of the above numbers.

[0033] Furthermore, the axis perpendicular to the base layer 1 and passing through the center of the top of the protrusion 11 is the central axis of the protrusion 11, and the horizontal distance between the central axes of the adjacent protrusions 11 is 1 μm to 20 μm. As an example, the horizontal distance between the central axes of the adjacent protrusions 11 can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 20 μm, or within the range of any combination of the above numbers. Preferably, the distance between the central axes of the adjacent protrusions 11 is 1 μm to 11 μm. As a result of long-term experimental verification, when within the above range, the sheet resistance uniformity is better.

[0034] Furthermore, the protrusions on the surface of the base layer are distributed such that the distance between the central axes of adjacent protrusions is D, and the ratio of the number of protrusions with 2 μm ≤ D ≤ 11 μm is 70% or more. Due to the above distribution, the presence of surface defects in the base layer is reduced. As a result, the defects in the first resistive layer deposited on the surface thereof are further reduced, the thickness of the first resistive layer becomes more uniform, and finally, the sheet resistance uniformity of the manufactured first resistive layer becomes better.

[0035] To further improve the sheet resistance uniformity of the first resistive layer, the protrusions on the surface of the base layer are distributed such that the ratio of the number of protrusions with 2 μm ≤ D < 4 μm is 10% - 40% (for example, 17%), the ratio of the number of protrusions with 4 μm ≤ D < 6 μm is 40% - 70% (for example, 55%), the ratio of the number of protrusions with 6 μm ≤ D < 8 μm is 10% - 40% (for example, 19%), the ratio of the number of protrusions with 8 μm ≤ D ≤ 11 μm is 5% - 20% (for example, 9%), and the ratio of the number of protrusions with 2 μm ≤ D ≤ 11 μm is 100%. The sheet resistance uniformity of the resistor manufactured within the above range of the distance between the central axes and the ratio of the number of protrusions is further improved.

[0036] Note that the "ratio" in this embodiment refers to the ratio of the number of protrusions satisfying certain conditions to the total number of protrusions in at least a partial region of the surface of the base layer. For example, "the ratio of the number of protrusions with 2 μm ≤ D < 4 μm is 10% - 40%" can mean that the ratio of the number of protrusions satisfying 2 μm ≤ D < 4 μm on the entire surface of the base layer to the total number of protrusions on the entire surface of the base layer is 10% - 40%, and it can also mean that the ratio of the number of protrusions satisfying 2 μm ≤ D < 4 μm in a partial region of the surface of the base layer to the total number of protrusions in that region is 10% - 40%.

[0037] In this embodiment, the thickness of the first resistive layer 2 is 5 nm to 3 μm. Preferably, the thickness of the first resistive layer 2 is 5 nm to 200 nm. Since the thickness of the first resistive layer 2 is thin, the shape of the first resistive layer 2 basically coincides with the shape of the surface of the base layer having the protrusions 11, that is, the first resistive layer 2 is arranged in the same shape as the base layer 1. Specifically, there are also protrusions 11 corresponding to the protrusions 11 of the base layer on the surface of the first resistive layer 2, and the dimensions are basically the same. As an example, the thickness of the base layer 1 may be 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm or 18 μm, and the thickness of the first resistive layer 2 may be 10 nm, 25 nm, 50 nm, 75 nm, 100 nm, 125 nm, 150 nm, 175 nm, 200 nm.

[0038] In this embodiment, the material of the base layer is a conductive material or a dielectric material, and the base layer may be a single-layer structure or a laminated multi-layer structure.

[0039] Examples of the conductive material include at least one of copper, aluminum, titanium, zinc, iron, nickel, chromium, cobalt, silver, and gold, but are not limited thereto. Specifically, the base layer may be a copper foil, an aluminum foil, a titanium foil, a zinc foil, an iron foil, a nickel foil, a chromium foil, a cobalt foil, a silver foil or a gold foil, or an alloy foil containing at least two of copper, aluminum, titanium, zinc, iron, nickel, chromium, cobalt, silver, and gold, or a composite base material composed of at least two of copper foil, aluminum foil, titanium foil, zinc foil, iron foil, nickel foil, chromium foil, cobalt foil, silver foil, and gold foil. Examples of the dielectric material include PET, PP, PS, ABF film, BT resin, polyacrylic acid, polyurethane, polyimide, etc., but are not limited thereto. In the base layer having a multi-layer structure, the materials of each layer may be the same or different.

[0040] The first resistance layer is an important functional layer of the composite substrate and is used to realize the resistance function of the embedded resistance. Different materials can be selected for the first resistance layer according to different functional requirements, so the first resistance layer has different resistance characteristics. Specifically, the material of the first resistance layer contains at least one element of Ni, Cr, Si, P, N, Ti, Pt, Ta, Mo, Sn, and O. Specifically, the material can be at least one of NiCrSi, NiCrAlSi, NiP, NiCr, AlN, TiN, Pt, Cr, Cr-SiO, Cr-Si, Ti-Si, Ti-W, TaN, Mo, and Ni-Sn materials. The first resistance layer may have a single-layer structure or a laminated multi-layer structure. In the first resistance layer with a multi-layer structure, the materials of each layer may be the same or different.

[0041] In this embodiment, at least one method of electroplating, chemical plating, physical vapor deposition, and chemical vapor deposition is used to form the first resistance layer, and the sheet resistance of the first resistance layer is 1 Ω to 2000 Ω.

[0042] It should be noted that all relevant parameters such as the thickness of the base layer, the thickness and maximum width of the first resistance layer in this embodiment are obtained by preparing slices of the composite substrate sample and then measuring them with a scanning electron microscope. The magnification of the scanning electron microscope is 2000 to 70000 times.

[0043] Referring to FIG. 4, as an optional embodiment, the composite substrate further includes a film layer 3 located on the surface of the first resistance layer 2 away from the base layer 1. On the one hand, the film layer can protect the first resistance layer 2 and prevent the first resistance layer 2 from being damaged by external forces. On the other hand, when the composite substrate is adhered to the circuit board, the film layer can adhere the first resistance layer 2 and the circuit board. Therefore, the peel strength between the composite substrate and the circuit board is further improved, the composite substrate is less likely to be peeled off from the circuit board, and the structural stability of the electronic device is improved. Further, after the film layer is provided, a foil board can be manufactured and directly applied to a PCB rigid substrate or a flexible substrate.

[0044] Specifically, the thickness of the film layer is 0.5 μm to 100 μm. As examples, the thickness of the film layer is 2 μm, 5 μm, 7 μm, 10 μm, 12 μm, 15 μm, 20 μm, 30 μm, 40 μm, 55 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm. The film layer is selected from at least one of polystyrene-based thermoplastic resins, vinyl acetate-based thermoplastic resins, polyester-based thermoplastic resins, polyethylene-based thermoplastic resins, polyamide-based thermoplastic resins, rubber-based thermoplastic resins, acrylic-based thermoplastic resins, phenol-based thermosetting resins, epoxy-based thermosetting resins, thermoplastic polyimide-based thermosetting resins, urethane-based thermosetting resins, melamine-based thermosetting resins, alkyd-based thermosetting resins, and ABF resins.

[0045] As examples, the film layer is selected from at least one of modified epoxy resins, modified acrylic resins, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polyethylene naphthalate, polystyrene, polyvinyl chloride, polysulfone, polyphenylene sulfide, polyether ether ketone, polyphenylene ether, polytetrafluoroethylene, liquid crystal polymer, polyparabanic acid, epoxy glass cloth, and BT resin. The specific thickness and material of the film layer are selected and set by those skilled in the art according to actual requirements.

[0046] Furthermore, referring to FIG. 5, in one embodiment, in addition to the film layer 3 being provided on the composite substrate, a conductive layer 4 is provided on the side of the film layer 3 away from the first resistive layer 2, thereby forming a foil-covered board including the first resistive layer. This foil-covered board has a four-layer structure and can be directly applied to a rigid substrate or a flexible substrate. Specifically, the conductive layer may have a single-layer structure or a laminated multi-layer structure. That is, the conductive layer may be a copper foil, an aluminum foil, a titanium foil, a zinc foil, an iron foil, a nickel foil, a chromium foil, a cobalt foil, a silver foil, or a gold foil, or an alloy foil containing at least two of copper, aluminum, titanium, zinc, iron, nickel, chromium, cobalt, silver, and gold, or a composite substrate composed of at least two of copper foil, aluminum foil, titanium foil, zinc foil, iron foil, nickel foil, chromium foil, cobalt foil, silver foil, and gold foil. The material of the conductive layer and the material of the base layer may be the same or different, and those skilled in the art can set it according to actual needs.

[0047] Furthermore, referring to FIG. 6, in one embodiment, a second resistive layer 5 is provided between the film layer 3 and the conductive layer 4, thereby forming an asymmetric structure. The material of the second resistive layer may be the same as or different from the material used for the first resistive layer 2, and those skilled in the art can set it according to actual needs. In this embodiment, at least one of electroplating, chemical plating, physical vapor deposition, and chemical vapor deposition is used to form the second resistive layer.

[0048] Note that the protrusions in this embodiment are formed by the deposition of fine crystal grains. As shown in FIG. 1, the height of the protrusions is higher than the bottom surface of the conductive layer.

[0049] This embodiment also provides a circuit board including the above composite substrate. This circuit board has all the advantages of the above composite substrate, which are omitted here.

[0050] Hereinafter, specific examples and comparative examples are exemplarily provided to support the technical effects of the technical solutions of this application. Here, the composite substrates in the examples and comparative examples both include a base layer and a first resistive layer. One surface of the base layer has several protrusions, and the first resistive layer is laminated on the surface of the base layer having protrusions. The base layer is a copper foil with a thickness of 18 μm, the material of the first resistive layer is NiCr alloy, and the thickness of the first resistive layer is 22 nm.

[0051] (Example 1) In this example, the surface roughness Ra of the base layer having the above protrusions is 0.8 μm, the number of protrusions is 1.0×10 3 per mm, the distance between the central axes of adjacent protrusions is D, and the protrusions on the surface of the base layer are distributed such that the proportion of the number of protrusions with 2 μm ≤ D < 4 μm is 10%, the proportion of the number of protrusions with 4 μm ≤ D < 6 μm is 50%, the proportion of the number of protrusions with 6 μm ≤ D < 8 μm is 30%, and the proportion of the number of protrusions with 8 μm ≤ D < 11 μm is 10%.

[0052] (Example 2) The only difference between the composite substrate according to this example and the composite substrate according to Example 1 is that in the composite substrate according to this example, the number of protrusions is 0.1×10 3 per mm.

[0053] (Example 3) The only difference between the composite substrate according to this example and the composite substrate according to Example 1 is that in the composite substrate according to this example, the number of protrusions is 3.0×10 3 per mm.

[0054] (Example 4) In this example, the surface roughness Ra of the base layer having the above protrusions is 0.8 μm, the number of protrusions is 0.1×10 3It is 0.1×10

[0055] (Example 5) In this example, the surface roughness Ra of the base layer having the above protrusions is 0.8 μm, and the number of protrusions is 0.1×10 3 per mm, the distance between the central axes of adjacent protrusions is D, and the protrusions on the surface of the base layer are distributed such that the proportion of protrusions with 2 μm ≤ D < 4 μm is 10%, the proportion of protrusions with 4 μm ≤ D < 6 μm is 40%, the proportion of protrusions with 6 μm ≤ D < 8 μm is 40%, and the proportion of protrusions with 8 μm ≤ D < 11 μm is 10%.

[0056] (Example 6) In this example, the surface roughness Ra of the base layer having the above protrusions is 0.8 μm, and the number of protrusions is 0.1×10 3 per mm, the distance between the central axes of adjacent protrusions is D, and the protrusions on the surface of the base layer are distributed such that the proportion of protrusions with 2 μm ≤ D < 4 μm is 40%, the proportion of protrusions with 4 μm ≤ D < 6 μm is 45%, the proportion of protrusions with 6 μm ≤ D < 8 μm is 10%, and the proportion of protrusions with 8 μm ≤ D < 11 μm is 5%.

[0057] (Example 7) In this example, the surface roughness Ra of the base layer having the above protrusions is 0.8 μm, and the number of protrusions is 0.1×10 3 per mm, the distance between the central axes of adjacent protrusions is D, and the protrusions on the surface of the base layer are distributed such that the proportion of protrusions with 2 μm ≤ D < 4 μm is 20%, the proportion of protrusions with 4 μm ≤ D < 6 μm is 50%, the proportion of protrusions with 6 μm ≤ D < 8 μm is 10%, and the proportion of protrusions with 8 μm ≤ D < 11 μm is 20%.

[0058] (Example 8) In this embodiment, the surface roughness Ra of the base layer having the protrusions is 0.8 μm, the number of protrusions is 0.1×10 3 protrusions per mm, the distance between the central axes of adjacent protrusions is D, and among the protrusions on the surface of the base layer, the proportion of the number of protrusions with 2 μm ≤ D < 4 μm is 10%, the proportion of the number of protrusions with 4 μm ≤ D < 6 μm is 70%, the proportion of the number of protrusions with 6 μm ≤ D < 8 μm is 15%, and the proportion of the number of protrusions with 8 μm ≤ D < 11 μm is 5%.

[0059] (Comparative Example 1) The only difference between the composite base material according to this comparative example and the composite base material according to Example 1 is that, in the composite base material according to this comparative example, the surface roughness Ra of the base layer having the protrusions is 6 μm.

[0060] (Comparative Example 2) The only difference between the composite base material according to this comparative example and the composite base material according to Example 1 is that, in the composite base material according to this comparative example, the number of protrusions is 4.0×10 3 protrusions per mm.

[0061] (Comparative Example 3) The only difference between the composite base material according to this comparative example and the composite base material according to Example 1 is that, in the composite base material according to this comparative example, the number of protrusions is 0.05×10 3 protrusions per mm.

[0062] (Test Example) For the composite base materials according to Examples 1 to 8 and Comparative Examples 1 to 3, a sheet resistance uniformity test and a peel strength test were conducted. In the sheet resistance uniformity test, first, the sheet resistance M at different positions of the composite base material was tested. The sheet resistance test points were evenly distributed on the surface of the composite base material, and the number of sheet resistance test points was 20. Next, the average sheet resistance value M ave of the composite base material at different positions was calculated, the sheet resistance maximum value M max and the sheet resistance minimum value M min were selected, and finally, the sheet resistance uniformity upper limit value = (M max - M ave ) / M ave × 100%, the sheet resistance uniformity lower limit value = (Mmin -M ave ) / M ave The upper limit value and the lower limit value of the sheet resistance uniformity were calculated according to ×100%. The test results are shown in Table 1.

[0063]

Table 1

[0064] It can be seen that in the technical solution of this embodiment, the sheet resistance uniformity is more excellent and the performance is more stable.

[0065] Obviously, the above embodiments are only examples for clarifying the description and do not limit the embodiments. Those skilled in the art can make other different forms of changes or modifications based on the above description. Here, it is not necessary and impossible to list all embodiments comprehensively. Also, obvious changes or modifications derived from this specification are still within the protection scope of the present invention.

Explanation of Reference Numerals

[0066] 1... Base layer, 11... Protrusion, 2... First resistance layer, 3... Film layer, 4... Conductive layer, 5... Second resistance layer.

Claims

1. It includes a first resistance layer and a base layer, the first resistance layer is laminated on at least one surface of the base layer, the surface of the base layer facing the first resistance layer has a plurality of protrusions, the surface roughness Ra of the base layer having the protrusions is 0.5 μm to 5 μm, and the number of the protrusions is 0.1×10 3 pieces / mm to 3×10 3 pieces / mm. Composite substrate.

2. The axis at the center of the top of the protrusion in the base layer is the central axis of the protrusion, and the horizontal interval between the central axes of adjacent protrusions is 1 μm to 20 μm. The composite substrate according to Claim 1.

3. The protrusions on the surface of the base layer are distributed such that the interval between the central axes of adjacent protrusions is D, and the proportion of the number of protrusions with 2 μm ≤ D ≤ 11 μm is 70% or more. The composite substrate according to Claim 1.

4. The protrusions on the surface of the base layer are distributed such that the proportion of the number of protrusions with 2 μm ≤ D < 4 μm is 10% - 40%, the proportion of the number of protrusions with 4 μm ≤ D < 6 μm is 40% - 70%, the proportion of the number of protrusions with 6 μm ≤ D < 8 μm is 10% - 40%, the proportion of the number of protrusions with 8 μm ≤ D < 11 μm is 5% - 20%, and the proportion of the number of protrusions with 2 μm ≤ D < 11 μm is 100% or less. The composite substrate according to Claim 3.

5. The thickness of the first resistive layer is 5 nm to 3 μm. The composite substrate according to Claim 1.

6. The material of the base layer is a conductive material or a dielectric material. The composite substrate according to Claim 1.

7. The composite substrate includes a film layer located on the surface of the first resistive layer away from the base layer. The composite substrate according to Claim 1.

8. The thickness of the film layer is 0.5 μm to 100 μm. The composite substrate according to Claim 7.

9. A conductive layer is provided on the side of the film layer away from the first resistive layer. The composite substrate according to Claim 7.

10. The conductive layer is a single-layer conductive layer or a multi-layer conductive layer. The composite substrate according to Claim 9.

11. A second resistive layer is provided between the film layer and the conductive layer. The composite substrate according to Claim 9.

12. The first resistive layer is formed by one or more methods among electroplating, chemical plating, physical vapor deposition, and chemical vapor deposition. The composite substrate according to Claim 1.

13. Including the composite substrate according to any one of Claims 1 to 12. Circuit board.

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